"Tropical Storm Isaac swirled over the Caribbean on Wednesday and was forecast to become a hurricane as it moved on a track that would put it off the coast of Florida on Monday, the opening day of the Republican National Convention in Tampa."

"Isaac was already dumping heavy rains on the Leeward Islands on Wednesday afternoon and hurricane watches were in effect for many places, including Puerto Rico and the U.S. and British Virgin Islands.

Isaac could also potentially threaten U.S. energy interests in the Gulf of Mexico, weather experts said. It was centered about 75 miles east-northeast of Dominica early on Wednesday afternoon, the U.S. National Hurricane Center (NHC) said."